1. Field of the Invention
The present invention relates to a rotary vibration damping device for damping rotary vibrations in a drive train through which the output torque of an internal combustion engine is transmitted in a drive power flow direction to the driving wheels of a motor vehicle.
2. Discussion of the Prior Art
A rotary vibration damping device of this type is known from the German reference DE 195 17 605 A1. Rotary vibration damping devices are responsible for reducing or completely suppressing rotational irregularities that occur in the drive train during the operation of a motor vehicle. Such rotational irregularities arise due to the out-of-round running of internal combustion engines, for example, and are transmitted to the entire drive train, causing potential discomfort to the vehicle driver or passengers. In the rotary vibration damping device known from DE 195 17 605 A1, a first centrifugal mass arrangement in the form of the input part of a torsional vibration damper is connected in rotation-proof fashion to the crank shaft. The output part of the torsional vibration damper, which constitutes the second centrifugal mass arrangement and, at the same time, the flywheel for a friction clutch, is connected to the torsional damper input part by torsional damping springs, and thus can be rotated relative to the torsional damper input part as well as with the torsional damper input part around the rotational axis. Further., a third centrifugal mass arrangement is mounted in rotatable fashion on the crank shaft. The third centrifugal mass arrangement is also connected to the torsional vibration damper input part, i.e., to the first centrifugal mass arrangement, via a planetary gearset. A planetary carrier is held in rotation-proof fashion on a fixed housing part. The torsional vibration damper input part is a ring gear, and a sun gear is arranged on the third centrifugal mass arrangement. By means of the planetary gearset, the number of rotations of the crank shaft is transmitted to the third centrifugal mass arrangement in increased fashion and reversed rotational sense.
Due to the relatively high mass inertia moments created by rotary vibration damping devices of this type, such devices have the disadvantage that the internal combustion engine responds relatively poorly to speed changes intended by the driver, especially in the range of higher speeds, because the additional mass must bc accelerated or slowed down.
From German reference DE 36 43 272 A1, a rotary vibration damping device is known, in which an additional damping mass is connected in rotary drive fashion to a clutch output shaft, i.e., to a transmission input shaft. In the case of this known rotary vibration damping device, a torsional vibration damper is provided in the drive train in a clutch disk. In the torsional vibration damper, two parts that are mounted one atop the other via springs can be rotated relative to each other for the purpose of vibration damping. In other words, in this known device, the additional damping mass is located in the drive train after the spring device of the torsional vibration damper in the driving force flow direction, and thus substantially impairs the vibrational behavior of the section of the drive train that follows the torsional vibration damper. The aforementioned document also discloses the disconnection of the additional damping mass from the transmission input shaft when a certain speed is exceeded, for the purpose of relieving the friction surfaces that are created by the clutch between the additional damping mass and the transmission input shaft during shifts in gear and transmission synchronization. After such disconnection of the additional damping mass from the transmission input shaft and upon a slight further increase in speed, this known rotary vibration damping device calls for the connection of the additional damping mass to the flywheel, which is linked in rotation-proof fashion to the crank shaft of the internal combustion machine, so as not to impair personal comfort. Thus, in this known device, there is a narrow speed window, below which the additional damping mass is connected to the transmission input shaft and above which the additional damping mass is connected to the flywheel, i.e. is connected to the drive train before the spring device of the torsion vibration damper in the drive power flow direction.